How Off-Road Tires Impact Wheel Bearings, Hubs, and Universal Joints
This article was originally published on Counterman.com.
Summer is right around the corner, and a bunch of off-road vehicles will be coming into your shop, most of which will have oversized tires. It’s important to be aware of how oversized tires place increased stress on wheel bearings, hubs, and U-joints.
Extra Stress on Wheel Bearings & Hubs
Wheel bearings and hubs perform reliably with stock tires. Larger off-road tires put bearings and hubs under extra strain. Several factors increase wear:
- Weight – A stock all season 31″ tire weighs about 40 lbs. A 35″ mud terrain tire can weigh 80 lbs. The tire weight only doubled, but the gyroscopic forces on the wheel bearing and hub are much more than doubled. Force increases exponentially with increases in mass.
- Increased Offset – Most oversize tires are on wheels that are offset so the tires don’t rub. This moves the load on the bearing to the outside, so the load on the bearing is no longer centered.
- Increased Leverage – A larger tire is a longer lever. A heavier tire puts more force on the lever. A long lever with more force behind it puts greatly increased leverage on the bearing and hub.
- Aggressive Tread – Large tread blocks create more resistance to turning. They also create additional vibrations that wear a bearing over time.
Signs of Wheel Bearing & Hub Failure
- Clicking sound when making sharp turns.
- Low pitched rumbling.
- Grinding sound when in motion.
- Slight pull to one side.
Extra Strain on Universal Joints
Oversized tires can shorten the life of u-joints. There are several factors at work:
- Steep Driveline Angles – Stock u-joints are designed to operate at an angle of 1 to 3 degrees. Most vehicles with oversize tires are lifted. Even a 3″ lift can increase the operating angle of the u-joint to 5 or 6 degrees. The u-joint will function, but it will wear out faster.
- Leverage – A transfer case in low range greatly increases torque at low speeds. A larger tire acts as a longer lever and is more able to resist the torque. U-joints are in the middle of the unstoppable force and the immovable object.
- Aggressive Tread – Aggressive tread hooks up better and is less likely to slip. This is good for traction, but increases the torque on the U-joint.
Symptoms of U-Joint Failure
- Knocking sound when shifting gears.
- Vibration throughout the vehicle, more noticeable at higher speeds.
- Transmission/transfer case or differential fluid leak. Excess vibration can damage seals.
The Importance of Quality Replacement Parts
Nobody wants their vehicle to break down off road. Inspect the wheel bearings, hubs, and u-joints for your off-roading customers before they fail. High-quality aftermarket replacement parts last longer than stock parts. Some are specifically designed for off-road use.
When you need premium replacements, seek out these features:
- OE type ABS sensors.
- Pre-loaded hub bearings.
- Triple lip seals.
- Roll formed hub for higher assembly strength.
- Oversized elliptical shaped bearings.
- Rust proof finish.
- Triple seals.
- Fluorine-containing rubber seal.
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